DOE review panel urges "green light" for new LBL accelerator

January 17, 1992

By Lynn Yarris,

Researchers in LBL's Heavy Ion Fusion Accelerator Research (HIFAR) group have received the formal results of the DOE review of their proposal for constructing a $58 million ILSE (Induction Linac Systems Experiments) accelerator at LBL. Although the review took place last Nov. 18-19, the results made the wait worthwhile.

Members of the review panel, which was chaired by Richard Briggs, deputy director of the Superconducting Super Collider Laboratory, called the ILSE presentation "outstanding" and urged that DOE give it a green light.

"Obviously, we are very happy with the results of this review," said LBL physicist Tom Fessenden, the ILSE project leader. Fessenden, HIFAR leader Roger Bangerter, project manager Craig Fong, project advisors Edward Lee and Andy Faltens, project electrical engineer Lou Reginato, and Henry Rutkowski all made presentations for LBL. Presentations were also made by Alex Friedman, Mark Newton and Simon Yu of the Lawrence Livermore National Laboratory, which is collaborating on the project.

ILSE represents a major step forward for the heavy-ion approach to inertial-confinement fusion, in which small pellets of thermonuclear fuel are compressed to the point of burning by beams of heavy ions. The project is designed to answer physics questions about controlling and manipulating the heavy ion beams.

"ILSE will address many of the remaining scientific and technical issues at a relevant scale," said Bangerter in his presentation to the review committee. "It will be a flexible experimental tool that should provide the data needed to determine the feasibility and cost of heavy ion fusion."

The DOE review dealt mainly with the linear accelerator that has been proposed for ILSE. Basically, this accelerator would consist of an injector, an electrostatic focus accelerating section, and a magnetic focus accelerating section. Construction would begin in 1994 and be completed in 1996.

Under the current proposal, the injector will accelerate four individual beams of ions to 2 million electron volts (MeV) and send them into the electrostatic focus accelerator, which will boost the ions in the beams to 4.5 MeV. A transfer line will then ferry one of the four beams into the magnetic accelerator, where its ions will be lifted to 10 MeV.

Says Fessenden, "Once we have demonstrated that the linac works with a single beam, we will modify the transfer section to study the combination of four beams into one. Later experiments will study bending, focusing, drift, and current amplification of the ion beams."

The add-on sections for these experiments will give ILSE a J- shaped configuration. Fessenden says that if the physics and engineering studies are favorable, eventually the ends of the J could be connected to form a complete ring for a new 100 MeV "recirculating induction accelerator."

Heavy-ion fusion researchers got their own lift this past year when their work was, for the first time, included -- along with magnetic fusion -- as part of the DOE Office of Fusion Energy's overall effort in developing fusion as a source of energy. DOE's new National Energy Strategy calls for developing the best possible heavy ion fusion scheme, determining if it is viable, and, if it is, building a heavy ion fusion demonstration plant by the year 2025.